1. Field of the Invention
This present invention relates to an embedded transformer device, and more particularly to a multi-tap winding design for an embedded transformer device.
2. Description of the Related Art
Power supply devices typically use transformers as a portion of converter circuits. Embedded magnetic component transformer devices are advantageous, as they avoid bulky electrical windings and magnetic cores, which often contribute the most to the weight and size of the power supply device. Instead, an embedded design allows the transformer device to be miniaturized, reducing both its footprint on a circuit board and also reducing its production cost while still maintaining the electrical isolation requirements needed for safe and reliable operation.
As the voltage generated by, for example, a DC-to-DC converter depends both on the input (supply) voltage, the load conditions, and the properties of the transformer itself, it is often desirable to adjust the transformer to either provide a different output voltage, or to compensate for a change in the input voltage or the load conditions. These adjustments may be required during prototyping to allow the performance of the transformer device to be optimized. Adjustments are also useful during production, where a single modifiable or configurable transformer device may be used across a range of different products as an alternative to using separately configured transformer devices for each product in the range.
In particular, it is desirable to be able to vary the turn ratio to adjust the extent to which the input voltage is stepped up or down, for example to accommodate changes in supply voltage or loading.
In conventional transformers, the turn ratio between the primary and secondary windings may be changed by winding extra turns or unwinding excess turns from the magnetic core. In a planar transformer, turns may be added or removed by cutting or linking conductive tracks or traces on the outer layer of the planar printed circuit board. However, these techniques of adding or removing turns are not generally possible in an embedded transformer, because the turns and the magnetic core are encased within a protective insulating substrate at the point of manufacture and are not easily accessible thereafter.
Thus, there is a need to provide an embedded transformer device in which the turn ratio can be modified.